The invention relates to a method and to a device for injecting a gaseous medium, in particular a gaseous fuel, into the intake tract of a gas engine or diesel-gas engine.
Electromagnetically actuable gas valves for injecting gaseous fuels into an intake tract of an engine are generally known. Such valves may in this case be used in such a way as to be combined to form a central injection unit for supplying gaseous fuel to multiple cylinders of the engine (central gas injection—“CGI”), or a separate gas valve is provided for each cylinder (multipoint injection—“MPI”).
A generic gas valve emerges for example from the laid-open specification DE 199 05 721 A1. To provide a large passage cross section while simultaneously realizing short switching and response times, said document proposes a gas valve which is in the form of a flat-seat valve. Said valve has a planar valve seat and a sealing element with at least one planar sealing surface facing toward the valve seat. Said construction is intended to permit valve cross sections of up to 10 mm2, it being the intention to be able to realize reliable switching of such valve cross sections with simultaneously short switching times.
A further gas valve, likewise in the form of a flat-seat valve, is also known from WO 2009/152414 A2.
During the injection of a gaseous medium, in particular of a gaseous fuel, into the intake tract of a gas engine or diesel-gas engine, the pressure of the gaseous medium and the opening duration of the valve determine the gas volume that is injected into the intake tract. For volume control, it is for example possible for the energization of an electromagnet, by means of which the gas valve can be actuated, to be varied in order to realize a short or long opening duration, and in order to thus inject a small or large fuel volume.
Since modern engines are often operated under extreme lean conditions (λ>1), it is particularly important to ensure a homogeneous fuel-air mixture in the cylinder of the engine. The fuel-air mixture is formed in the intake tract between the gas valve and combustion chamber. Here, the length of the flow path from the gas valve to the combustion chamber may be decisive of whether a homogeneous mixture formation, which ensures a uniform combustion of the gas mixture in the combustion chamber, is achieved.
Taking the abovementioned prior art as a starting point, it is the object of the present invention to specify a method and a device for injecting a gaseous medium into an intake tract of an engine, which method and device promote a homogeneous mixture formation in the intake tract.